JP3731399B2 - Screw compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to, for example, a screw compressor that compresses a gas such as a refrigerant.
[0002]
[Prior art]
Conventionally, this type of screw compressor is shown in FIG. In this screw compressor, a screw rotor 3 is fitted into a cylinder 2 formed in a casing 1. The screw rotor 3 meshes with a substantially rotor-shaped gate rotor body 6 of the gate rotor 5 (in FIG. 3, only one gate rotor 5 is shown, but the gate rotor has 2 points symmetrical with respect to the center. There is one.) The gate rotor 5 is supported at both ends by a both-end bearing structure B2 with respect to the gate rotor body 6. That is, the shaft portions 7 and 8 protrude from both sides of the gate rotor body 6, and one shaft portion 7 is supported by the rolling bearings 10 and 11 held by the bearing housing 9, while the other bearing 8 is the bearing. The gate rotor 5 is supported at both ends by being supported by a rolling bearing 13 held by the housing 12.
[0003]
[Problems to be solved by the invention]
Thus, in the conventional screw compressor, since the gate rotor 5 is supported at both ends by the double-end bearing structure B2, the two bearing housings 9 and 12 and the rolling bearings on both sides are provided for each gate rotor 5. 10, 11 and 13 are required, resulting in a problem that the number of parts increases, the manufacturing cost increases, and the assemblability and maintainability are poor.
[0004]
In the conventional screw compressor, the screw rotor 3 is almost occupied by the two gate rotors 5 (only one is shown in FIG. 3) and the both-end supported bearing structure B2. The high pressure chamber into which the discharge gas enters around the cylinder 2 cannot be provided on the suction side of the gate rotor 5 by being obstructed by them. Therefore, there is a problem that the cylinder 2 and the screw rotor 3 come into contact with each other due to a difference in thermal expansion due to a temperature difference between the screw rotor 3 and the cylinder 2 during seizure or soaking at the time of liquid back during transition or during wet operation. there were. Further, if the gap between the cylinder 2 and the screw rotor 3 is increased in order to avoid this contact, there is a problem that the efficiency decreases due to gas leakage.
[0005]
Therefore, the object of the present invention is to reduce the number of parts of the bearing structure of the gate rotor, to reduce the manufacturing cost, to improve the assemblability and maintainability, and to the cylinder and screw rotor on the suction side from the gate rotor. It is an object of the present invention to provide a screw compressor that can improve the reliability and efficiency by reducing the difference in temperature and reducing the difference in thermal expansion.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the screw compressor of the invention of claim 1 comprises:
A screw rotor that fits into a cylinder formed in the casing;
A gate rotor having a gate rotor body meshing with the screw rotor and a shaft portion projecting to one side of the gate rotor body;
A cantilever bearing structure for cantilevering the gate rotor with respect to the gate rotor body by the shaft portion ;
A high-pressure chamber (55) that is formed in the casing so as to be located outside the cylinder and extends from the discharge side to the suction side than the gate rotor, and stores discharge gas;
A plurality of the high-pressure chambers are spaced apart from each other so as to surround the periphery of the cylinder .
[0007]
According to the screw compressor configured as described above, the shaft portion on one side of the gate rotor body is supported by the cantilever bearing structure, and the gate rotor is cantilevered with respect to the gate rotor body. Therefore, this screw compressor can reduce the number of parts such as bearing housings and bearings by about half compared with the case where the gate rotor is supported at both ends, greatly reducing the manufacturing cost, and greatly improving assembling and maintenance. it can.
[0009]
Further, the screw compressor having the above configuration uses the space of the casing that is generated when the gate rotor is supported by the cantilever bearing structure, and extends the gate rotor further from the discharge side to the suction side, so that the outside of the cylinder. A high pressure chamber located at is formed. A high-temperature discharge gas is accommodated in the high-pressure chamber. For this reason, the cylinder tends to be cooled at the time of liquid back at the time of transition or during wet operation, but the cylinder is warmed by the high-temperature discharge gas contained in the high-pressure chamber, and the temperature difference between the screw rotor and the cylinder is small. Thus, the cylinder and the screw rotor are not in contact with each other due to the difference in thermal expansion, and the reliability is improved. In addition, since the difference in thermal expansion between the cylinder and the screw rotor is reduced, the gap between the cylinder and the screw row is reduced, gas leakage is reduced, and the efficiency can be improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0011]
As shown in FIG. 1, this screw compressor has a compression portion 22 and a motor 23 arranged in a casing 21 in which cover portions 19 and 20 are fixed to both ends of a casing body 18. The compression unit 22 is rotatably fitted in a cylinder 25 formed in the casing body 18 with a screw rotor 26 formed integrally with one end of a main shaft 27. A rotor 28 of the motor 23 is fixed to the other end of the main shaft 27. A stator 29 of the motor 23 is fixed to the casing body 18.
[0012]
The main shaft 27 is supported by the first rolling bearings 31 and 32 on the outer end side of the screw rotor 26, and the main shaft 27 is supported on the bearing housing 33 formed on the cover portion 19 on the outer end side of the rotor 28 of the motor 23. The main shaft 27 is supported at both ends by the first and second rolling bearings 31, 32, and 35 with respect to the rotor 28 and the screw rotor 26 that are supported by the held second rolling bearing 35. As described above, the portion between the first rolling bearings 31 and 32 and the second rolling bearing 35 of the main shaft 27 supported at both ends by the first and second rolling bearings 31, 32 and 35 is cantilevered. Unlike the support, manufacturing errors of the first and second rolling bearings 31, 32, 35, displacement due to misalignment, and eccentricity are not amplified, so that the first rolling bearings 31, 32 of the main shaft 27 are not amplified. The rotor 28 and the screw rotor 26 that are fixed to or integrated with the portion between the second rolling bearing 35 and the screw rotor 26 can be accurately arranged at desired positions. Therefore, the air gap between the stator 29 and the rotor 28 of the motor 23 does not become uneven, and it is possible to prevent the generation of a beep or abnormal noise.
[0013]
The bearing housing 33 of the cover part 19 is connected to the outer shell part 38 of the cover part 19 by four ribs 36. The cover portion 19 is fixed to the casing body 18 with a bolt 37 after adjusting the position so that the second rolling bearing 35 held in the bearing housing 33 is concentric with the first rolling bearings 31 and 32. is doing.
[0014]
On the other hand, a centering guide 41 located between the rotor 28 and the screw rotor 26 is formed in the casing body 18 of the casing 21. As shown in FIG. 2, the centering guide 41 is provided at four positions with a phase of 90 degrees. When the main shaft 27 and the first and second rolling bearings 31, 32, 35 are assembled, the main shaft 27 is inserted inside the centering guides 41, 41, 41, 41 so that the main shaft 27 can be easily centered. To be done. The inner portions of the end faces of the centering guides 41, 41, 41, 41 on the screw rotor 26 side are respectively tapered surfaces 43, and the main shaft 27 is placed on the inner side of the centering guides 41, 41, 41, 41. When inserted from the side into the motor 23 side, the tapered surface 43 allows the main shaft 27 to be easily inserted into the centering guides 41, 41, 41, 41.
[0015]
Further, as shown in FIG. 1, the refrigerant is sucked into the compression portion 22 through the refrigerant suction passage 42 as indicated by an arrow G. The refrigerant suction passage 42 passes between the centering guides 41, 41, 41, 41, that is, in the vicinity of the main shaft 27. The cooling fin 44 of the rotor 28 of the motor 23 protrudes from the narrow portion of the refrigerant suction passage 42 located in the vicinity of the main shaft 27 so that the liquid refrigerant is cooled by the cooling fins 44 even if the suction passage 42 is returned to the liquid. The gas is pulverized and atomized to be sucked into the cylinder 25. In this way, liquid compression is prevented.
[0016]
Further, as shown in FIG. 2 which is a sectional view taken along line II-II in FIG. 1, the casing main body 18 of the casing 21 is provided with gate rotors 51 and 51 which are point-symmetric in an oblique direction. The gate rotors 51 and 51 are cantilevered by cantilever bearing structures B1 and B1, respectively. That is, the gate rotor 51 includes a gear-shaped gate rotor main body 52 that meshes with the screw rotor 26, and a shaft portion 53 that projects only on one side of the gate rotor main body 52. The gate rotor 51 is cantilevered with respect to the gate rotor main body 52 by being supported by the rolling bearings 62 and 63 accommodated in the main body. That is, a gate rotor is constituted by a cantilever bearing structure B1 including a bearing housing 61, bearings 62 and 63 held by the bearing housing 61, a pressing plate 64, and a coil spring 65 that presses the bearing 62 against the pressing plate 64. 51 is cantilevered with respect to the gate rotor body 52. The bearing housing 61 is fixed to the casing 21 with bolts 66 together with the pressing plate 64.
[0017]
As shown in FIG. 2, suction is performed from the discharge side (right side of the line II-II in FIG. 1) through the region of the casing body 18 where the cantilever bearing structure B <b> 1 and the gate rotor 51 do not exist. A high pressure chamber 55 is formed that extends to the side (left side of the line II-II in FIG. 1) and is located outside the cylinder 25. A high temperature discharge gas is introduced into the high pressure chamber 55. A part of the high pressure chamber 55 is located outside the low pressure chamber 56 as shown in FIG.
[0018]
In the screw compressor having the above-described configuration, as shown in FIG. 2, the casing main body 18 of the casing 21 is provided with gate rotors 51 and 51 in a point-symmetrical manner in an oblique direction, and each of the gate rotors 51 and 51 is a cantilever bearing structure. The gate rotor main bodies 52 and 52 are cantilevered by B1 and B1. As described above, the shaft portion 53 on one side of the gate rotor body 52 is supported by the cantilever bearing structure B1, and the gate rotor 51 is cantilevered with respect to the gate rotor body 52. Compared to the case where both are supported, the number of parts such as the bearing housing 61 and the bearings 62 and 63 can be reduced to about half, the manufacturing cost can be reduced, and the assemblability and maintainability can be greatly improved.
[0019]
The high-pressure chamber 55 that extends from the discharge side to the suction side from the discharge side to the high-pressure chamber 55 using the space of the casing 21 that is generated when the gate rotor 51 is cantilevered by the cantilever bearing structure B1 has a high temperature. The discharge gas is guided, and the cylinder 25 is warmed by the heat of the discharge gas. Therefore, the suction side of the cylinder 25 tends to be cooled at the time of liquid back at the time of transition or during wet operation, but the cylinder 25 is warmed by the high-temperature discharge gas stored in the high-pressure chamber 55, and the screw rotor 26 and the cylinder The temperature difference from 25 is reduced. Therefore, the difference in thermal expansion between the screw rotor 26 and the cylinder 25 is reduced, and the screw rotor 26 and the cylinder 25 are not seized or so-called galling occurs, thereby improving the reliability.
[0020]
Further, as described above, since the difference in thermal expansion between the cylinder 25 and the screw rotor 26 is reduced, the gap between the cylinder 25 and the screw rotor 26 can be reduced to reduce gas leakage and improve efficiency. .
[0021]
In the above embodiment, the cantilever bearing structure B1 includes the bearing housing 61, the bearings 62 and 63, the pressing plate 64, and the coil spring 65, but the cantilever bearing structure does not include the bearing housing. The bearing may be directly attached to the casing, and the pressing plate 64 and the coil spring 65 may be omitted. The cantilever bearing structure may be any structure as long as it supports a shaft portion protruding to one side of a gear-shaped gate rotor body and cantilever-supports the gate rotor with respect to the gate rotor body. The bearing may be a sliding bearing.
[0022]
In the above embodiment, the screw rotor 26 is formed integrally with the main shaft 27, but the screw rotor and the main shaft may be separate.
[0023]
【The invention's effect】
As can be seen from the above, according to the invention of claim 1, since the shaft portion on one side of the gate rotor body is supported by the cantilever bearing structure and the gate rotor is cantilevered with respect to the gate rotor body, the gate Compared to the case where the rotor is supported at both ends, the number of parts such as the bearing housing and the bearing can be reduced to about half, the manufacturing cost can be reduced, and the assembling property and the maintainability can be greatly improved.
[0024]
Further, according to the first aspect of the present invention, by utilizing the space of the casing caused by the gate rotor is supported by a bearing structure cantilevered even more gate rotors from the discharge side extends to the suction side of the cylinder Since the high-pressure chamber located on the outside is formed, the cylinder is about to be cooled at the time of liquid back at the time of transition and wet operation, but the cylinder is warmed by the high-temperature discharge gas stored in the high-pressure chamber, The temperature difference between the screw rotor and the cylinder is reduced, and the cylinder and the screw rotor are not brought into contact with each other due to the difference in thermal expansion, thereby improving the reliability. In addition, since the difference in thermal expansion between the cylinder and the screw rotor is reduced, the gap between the cylinder and the screw row is reduced, gas leakage is reduced, and the efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a screw compressor according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a cross-sectional view of a conventional screw compressor.
[Explanation of symbols]
21 Casing 26 Screw rotor 51 Gate rotor 52 Gate rotor main body 53 Shaft portion 55 High pressure chamber B1 Cantilever bearing structure

Claims (1)

A screw rotor (26) fitted into a cylinder (25) formed in the casing (21);
A gate rotor (51) having a gate rotor body (52) meshing with the screw rotor (26) and a shaft portion (53) projecting to one side of the gate rotor body (52);
A cantilever bearing structure (B1) for cantilevering the gate rotor (51) with respect to the gate rotor body (52) by the shaft portion (53) ;
A high pressure chamber (55) that is formed in the casing (21) so as to be located outside the cylinder (25) and extends from the discharge side to the suction side than the gate rotor (51) and accommodates discharge gas. Prepared,
The screw compressor, wherein a plurality of the high-pressure chambers (55) are present at intervals from each other so as to surround the cylinder (25) .

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